A Fluidized Bed Photocatalytic Reactor for Nitrate Conversion

PROJECT SUMMARYOpportunity: Nitrate contamination has emerged as the most pervasive groundwater pollutant inNorth America predominantly originating from agricultural activities and shifting nitrogen inputsto land surfaces. In the United States over 7 million people rely on community water systems(CWS) with nitrate concentrations exceeding the maximum contaminant level (MCL). A rigorouspeer-reviewed study by the Environmental Working Group indicates that nitrate pollution in USdrinking water may contribute to up to 12500 cancer cases annually with associated healthcarecosts reaching $1.5 billion. Current nitrate treatment technologies for CWSs generate highlyconcentrated nitrate brine residuals rendering them constrained by expensive brine disposal andmanagement processes. Moreover with over 35 million acres of sub-surface drained land in theUS no technology has yet established a significant market share for nitrate removal fromagricultural drainage. Given the vast extent of nitrate contamination in community water systemsand the increasing necessity to curtail nitrogen loads from tile drainage the market potential foreffective nitrate removal solutions is substantial.Project Objectives: The main technical objective of this project is to demonstrate and validate ahighly efficient photocatalytic denitrification unit for the sustainable removal of nitrates fromwastewater at a lower cost than incumbent technologies. In Phase I the team successfullydeveloped materials and systems that exhibit superior nitrate removal and conversion efficienciesexceeding 95%. These materials demonstrated a photon-to-chemical conversion efficiency of 2.5%and remained stable for 100 hours of operation. In Phase II the down-selected materials andsystems from Phase I will undergo extensive optimization testing and operation in lab-scale andmini-scale prototypes aiming to achieve photonic efficiencies greater than 10% nitrate conversionefficiencies surpassing 95% and stability exceeding 1000 hours. To accomplish these objectivesthe team will refine the physical and chemical composition of the Phase I catalyst to enhance itsphotoactivity and stability. Furthermore they will employ operando tools developed during PhaseI to investigate the catalyst's selectivity and corrosion mechanisms and assess their performancein lab-scale and mini-pilot plant-scale reactors. A comprehensive techno-economic analysis willalso be conducted to identify pathways for successful commercialization.Anticipated Results. By the end of Phase II Pani Clean Inc. will have developed a smallengineering-scale nitrate treatment unit that boasts nitrate conversion efficiencies and selectivityexceeding 95% eliminates brine disposal issues and costs less than $1.5 per 1000 gallons oftreated water. This represents a two-to-five-fold decrease in cost compared to incumbenttechnologies.Potential Commercial Applications. The immediate addressable market for Pani Clean Inc.'sinnovative nitrate treatment unit comprises the 1600+ community water systems (CWS) that haverecently experienced violations of nitrate levels primarily due to agricultural practices. In the nearterm point-of-use (POU) nitrate treatment systems for individual residences with nitrate- contaminated private wells will be targeted as well as treating nitrates at the edge-of-field practices.